JP1994-48147A discloses a suspension device. This suspension device includes dampers interposed between a body and wheels of a vehicle, actuators for adjusting damping forces generated by the dampers, a control device for controlling the actuators to control the damping forces generated by the dampers, spring upper acceleration sensors for detecting accelerations of spring upper members in a vertical direction, and a steering sensor for detecting a steering angle of a steering wheel.
This suspension device obtains a vertical speed of the spring upper member by integrating a vertical acceleration and calculates a bounce velocity, a pitching rate and a roll rate of the spring upper member. The suspension device also calculates a damping force to be generated by the damper by adding values obtained by multiplying these rates by proportional gains and causes the damper to generate the calculated damping force.
Further, this suspension device calculates a steering speed based on a rate of change of the steering angle and changes the value of the proportional gain, by which the roll rate is to be multiplied, according to this calculated steering speed to deal with a roll caused by sudden steering. That is, this suspension device increases the value of the proportional gain as the steering speed increases, whereby the roll of the vehicle body at the time of steering can be suppressed.